Partial discharge refers to a localized dielectric breakdown in a portion of the electrical insulation system of a device (e.g., a motor) when the insulation system is under high-voltage stress. The breakdown is caused by one or more cracks, voids, or inclusions in the insulation system. Partial discharges cause small, but significant, damage to the device, and indicate that the insulation system is beginning to fail, which may lead to catastrophic damage in the future. As such, it is desirable to detect partial discharges so that the insulation system is repaired or replaced before such damage occurs.
To detect partial discharges, a partial discharge detection board is coupled to the device and adapted to analyze signals from (e.g., reflected off of) the device to determine whether the device is experiencing partial discharges when the device is exposed to a particular voltage. The partial discharge detection board includes an analog-to-digital converter (“ADC”) that samples the signals at a sampling rate of, for example, 100 MHz. The ADC is unable to distinguish portions of the signal above the Nyquist frequency (e.g., 50 MHz in this example). Thus, conventional partial discharge detection boards include an anti-aliasing filter to remove portions of the signal above the Nyquist frequency.